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' W. S; CLARK, S. R. FARRINGTON 8'6 T. SHBARD.

TENSION DEVICE FOR SEWING MAGHINES= No. 278,096. Patented May 22,1883.

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our automatic varying tension device.

UNITED STATES WILLIAM s. CLARK,

PATENT OF ICE.

soUrH B. FARRINGTON, AND TITUS SHEARD, or

nrrrnn FALLS, New roan.

TENSION DEVICE FOR SEWING-MACHINES.

SPECIFICATION forming part of Letters Patent No.'278,096, dated May 22, 1883.

Application filed March 6, 1883. (N0 model.)

To all whom it may concern 4 Be it known that we, WILLIAM SHELDON CLARK, SOUTH R. FARRINGTON, and TITUS SHEARD, of Little Falls, in the county of Herkimer and State of New York, have invented new and useful Improvements in Sewing-Machine Thread-Tension Devices, of which the following, taken in connection with the accompanying drawings, is a full, clear; and exact description. y

This invention relates to that class of threadtension devices which automatically release or slacken the thread dnrin g the formation 'of the loop thereof, and thereby produce uniform stitches in any thickness of cloth without undue strain on the thread, and without requiring special attention of the operator.

The invention consists in the combination, with the tension device, of certain means for regulating the action thereof, so as to slacken or tighten the thread at any desired time during the movement of the needle; and it furthermore consists infa novel construction and combination of the details of the said tension device, all as hereinafter more fully described, and set forth in the claims.

Referring to the annexed drawings, Figure 1 is a side elevation of a Willcox 8t Gibbs sewing-machine provided with our invention. Fig. 2 is an enlarged detached plan view of Fig. 3 is an end view of the same. Fig. 4=is a longitudinal section of the tension device; and Fig. 5, a detached view of a tension-varying lever designed for use on shuttle machines.

Similar letters of reference indicate corresponding parts.

A represents the iron frame or standard of thesewin g-machine.

B denotes the needle-bar lever pivoted on said frame, and carrying on its free end the needle-bar O, to which the needle N is at-.

tached. The arrangement of the aforesaid parts, being generally understood by thepublic and forming no part of our invention, requires no detailed description.

The machine here illustrated forms the stitch of one thread by means of the so-ca-lled looper D, fixed to the end of the rotary mandrel E, while in the majority of machines the stitch is formed of two threads carried, respectively,

inthe needle and in the reciprocating shuttle underneath the table.

To the rear portion of thestandard A we secure our improved thread-tension, consisting of a short arm, P, which projects horizontally over the needle-bar lever B. Said arm is provided with a transverse slot, 8, and with a longitudinal channel extending from said slot to the free end of the arm, in 'which channel is fitted to slide endwise a spindle, a, which is screw-threaded part way of its length, and is provided on its outer end with a suitable manipulating-knob and a collar, b. The aforesaid channel is intersected by a longitudinal cavity, 0, in the arm P, and in the said cavity a nut, '12, is applied to the screw-threaded portion of the spindle.

Between the nut and outer end of the cavity 0 an expansive spiral spring, 4;, surrounds the spindle and presses the same inward or toward the slot 8 before described.

Between the collar 1) and a. washer, b, adjacent to the end, of the arm 1?, is a circumferentially'grooved roller, d, mounted on the spindie. The sewing-thread, beingpassed around in the groove of said roller, is extended thence through an eye, a, on the needle-bar lever, and through the usual eyes, a and a, on the needle-bar guide, and through the'eye of the needle. By turning the spindle so as to run the nut a toward the outer end of the spindle, the spring v becomes compressed, and is caused to exert increased end-pressure on the spindle, thereby producing greater pressure against the two sides of the roller (1, and by the resultant friction on the same restrains the movement of the roller. The spindle a is of sufficientlength to partly protrude in the slot 8, for the purpose hereinafter explained.

L denotes a rod or lever pivoted on the nee die-bar lever B, and having its free end lying in the slot 8 of the arm P. Said free end of the lever L is beveled, and is caused to bear against the protruding end of the spindle a by a set-screw, e, inserted through the rear end of the arm I? and pressing against the leverL, the set-screw being soadjustable as to hold the thin portion of said lever against the spin- 1 drawin gs.

it imparts a reciprocating movement to the lever L, and this movementintermittently crowds. the beveled portion of said lever between the set screw 6 and the protruding end of the spindle a, thereby forcing the latter longitudinally toward the free end of the arm P, and consequently releasing the roller 1 of the frictional hold of the collar 1), which is on the spindle at the side of the roller, in the manner hereinbefore described.

On sewing-machines which form the loop of the thread during the descent of the needle, as is the case with the class of machines here represented, the lever L is to have its bevel at one side of the arm P, and on shuttle machines which form the loop of the thread during the rising of'the needle the aforesaid lever is to have its bevel at the opposite side of the arm .P, the different locations of the bevel being shown, respectively, in Figs. 2 and 5 of the The location of the set-screw e will be shifted on the arm P accordingly, as indicated by dotted lines in Fig.2 of the drawings.

The action of the lever L on the spindle a canbe regulated by means of the set-screw e, a greater or less protrusion of which in the slot 8 crowds the lever L toward the spindle a to a greater or less extent. Said set-screw also affords convenient means for compensating for the wear, and abrasion and for taking up lost motion. set-screw in or out the passage for the beveled end of the lever L through the slot 8 can be regulated so as to actuate the spindle in releasingthe rollerdand thus slacking thethread during any period of the rising and falling of the needle. When the spindle a is released from the pressure of the lever L it has its requisite tension, which is adjusted by turning the spindle, the spring 0, connected therewith, producing friction between the sides of the roller Furthermore, by setting the and the adjacent collar, 1), and a washer, b, on the spindle to, adjacent to .the arm P, in the manner hereinbefore described.

Having described my invention,whatI claim as new, and desire to secure by Letters Patent, 1s-

1. The lever'L, pivoted to the needle-bar lever, and having a beveled free end, in combination with the arm P, provided with the slot 8, and the spring-restrained spindle a, protruding in said slot and provided at its opposite end with two frictional bearings, and the roller 61, mounted on the spindle between said bearings, substantially as described and shown.

2. In combination with the leverL, the arm P, provided with the cavity 0 and slot 8, the screw-threaded spindle a passing through said cavity and into slot 8, and provided with the nut n and collar b, the spring 1:, applied to the spindle between the nut and outer end of the cavity 0, and the roller d, mounted on the screw between the end of the arm P and collar 6, all substantially as described and shown, for the purpose set forth.

3. The combinatiomwith the arm P, provided with the slot s, spring-restrained spindle a, carrying the roller d, and the lever L, having its beveled free end lying in the slot 8, as described, of-the set-screw e, substantially in the manner and for the purpose set forth.

In testimony whereof we have hereunto signed our names and affixed our seals, in the presence of two attesting witnesses, at Little Falls, in the county of Herkimer, in the State of New York, this 2d day of March, 1883.

Witnesses: e JAMES HART, FRANK SENIOR. 

